silylketenes under Kulinkovichconditions:alkene/ketene exchangs versus nucleophilic addition.Application to the stereoselective preparationof vinylcyclopropanols.

摘要

Silylketenes react under Kulinkovichconditions through two competitive pathways:alkene/ketene exchanges versus nucleophilic addition.In both cases,the organotitanium intermeidate reacts withan aldehyde to yieldan adduct whichcan undergo an elimination to yield a vinylcyclopropanol or an alpha,beta-unsaturatedcarbonyl compound.